AnnaE,
Can you post your sketch? That might be helpful. I have only included one, and have done a handful of these. These rooms actually have a name - natatorium. (learned that from one of our knowledgeable posters here).
In my case where I included the area, it was a centrally located room that had to be utilized for access to 3 of the 4 bedrooms and one of the baths. I couldn't 'wall off' the natatorium and retain functional access to the rest of the sleeping quarters and bath. It also was finished, heated, cooled, had a high ceiling with tongue and groove/beams, skylights, and solar equipment that helped heat other portions of the home.
In others that I've run across, the natatorium wasn't such an integral part of the floorplan and were it not to exist, the remainder of the floorplan would still function. In those cases, I didn't include it in the living area.